Imaging systems that can image tissue at a given depth within biological tissue are useful in a multitude of medical applications. In these medical applications, the imaging system commonly used in the field has an imaging assembly optically coupled to a probe having an elongated imaging lens generally provided in the form of a gradient-index (GRIN) lens. The elongated imaging lens has a longitudinal axis defined between two opposite ends thereof. One end is coupled to the imaging assembly while the other end, referred to as the tip, is inserted within the biological tissue for imaging thereof. The typical imaging system has a fixed focal point spaced from the tip along the longitudinal axis such that imaging of the biological tissue is limited to the fixed focal point.
Another imaging system commonly used for such application incorporates a mechanical actuator to move optical components of the imaging assembly in order to vary the focal point of the imaging system in the biological tissue. While allowing to image the biological tissue at a varying focal, such imaging systems suffer from drawbacks inherent to the presence of the mechanical actuator. Such drawbacks can be particularly significant in vivo applications, and more particularly for free-behaving animal experiments. There thus remains room for improvement.